The first 15 right-handed men with severe developmental dyslexia and their matched controls have been studied with EEG spectral analysis, event-related potentials, xenon inhalation procedures for measuring regional cerebral blood flow, neurological examinations for soft signs, and neuropsychological testing. In addition, ten patients have been studied with magnetic resonance head scans in pilot study. Subtle abnormalities of temporal symmetry are suggested by the preliminary finding that nine of ten patients show very symmetrical temporal lobe volumes, a finding compatible with neuropathological work on dyslexia. Cerebral blood flow data show group differences both in posterior (parietal) cortex and in frontal cortical regions. Event-related potential data suggest abnormalities in N100, N200, and P300 components, which differ qualitatively for dyslexic men with positive versus negative retrospective parent ratings for attention deficit disorder. Neuropsychological test data document continuing deficits in phonetic decoding and encoding, visual-verbal associative learning, verbal learning, and language processing in our adult dyslexic sample. Dyslexic children with and without attention deficit disorder, math-disabled children, pure ADD children, and controls are being recruited for event-related potential studies, and eye movement studies. We are beginning a controlled, quantitative MRI study of our dyslexic adults and planning a PET-scan of this sample.